Frame conversion for asynchronous input image signals

Television – Format – Including additional information

Reexamination Certificate

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Details

C348S441000, C348S153000, C348S705000, C348S715000, C348S478000

Reexamination Certificate

active

06317160

ABSTRACT:

BACKGROUND OF THE INVENTION
The invention relates to a frame converting device having a function to continuously output a plurality of image signals in a synchronized state while switching the image signals from a plurality of asynchronous inputs, and a function to extract a desired one of the continuous image signals from such plural inputs and outputs the extracted signal, and particularly, to improvement of a monitoring function when reproducing a recorded signal.
A known image switcher switches image signals from a plurality of cameras and the like and outputs the signals as one image signal. In switching such image signals, the input image signals from the cameras are often asynchronous with each other, but the disturbance of synchronous signals in the output image signals is inconvenient. In such case, all the input image signals are synchronized in advance by using a camera having a TBC (Time Base Corrector) function. Otherwise, asynchronous-synchronous conversion must be performed for each input by using a frame-converting device having a frame memory.
First problem: a camera having the TBC function is expensive, and therefore it is difficult to use the camera in a low-price route. Further, in the frame-converting device, the number of frame memories is the same as that of input image signals. While an image signal is stored into one of the frame memories, reading from another frame memory is performed.
Second problem: this type of device selects a either one of a first operation to switch the image signals from the plurality of cameras to outputs them as one image signal and to perform monitor display or VCR recording, or a second operation to extract a desired image signal from image signals from the plurality of cameras, switched to form one signal, and reproduced on a VCR or the like, and to perform display based on the extracted signal on the monitor.
In such frame-converting device, the number of frame memories must be the same as that of input image signals. This increases the price of the device. Further, the monitor display, and the VCR recording operation and cannot be performed in parallel to the VCR reproduction operation.
SUMMARY OF THE INVENTION
The present invention has been made to solve or at least mitigate the above-described problems, and has its object to realize a frame converting device which performs a first operation to continuously output a plurality of image signals in a synchronized state while switching the respective asynchronous image signals, by using fewer frame memories than the number of input image signals, in parallel to a second operation to extract a desired image signal from image signals switched to form one signal and to output the extracted signal.
Accordingly, a first aspect of the present invention provides a frame conversion device as recited in claim
1
. Advantageous embodiments are defined in the dependent claims.
This frame converting device time-divisionally stores and reads a plurality of image signals by means of less frame-conversion storage means than input image signals while switching the signal input means and the signal output means. Thus the device continuously outputs the image signals in a synchronized state while switching a plurality of asynchronous image signals with less frame memories than input signals.
Further, the device detects the identification signals included in the image signals in frame units, extracts frame timing of an image signal with a predetermined identification signal from the image signals in frame units, stores the image signal of the frame timing, and continuously outputs the image signal. Thus, the device extracts a desired image signal from image signals switched to form one signal, and outputs the extracted image signal.
As the device has the recording frame-converting unit and the reproduction frame unit, the device can perform these two operations in parallel.
As to claim
3
, the frame converting device can record the image signal from the recording frame-converting unit by the VCR, and when the recorded image is reproduced by the VCR, extract a desired image signal from image signals switched to form one signal by the reproduction frame unit.
As to claim
4
, when a desired image signal is extracted from image, switched to form one signal and outputted the frame-converting device can extract the desired image signal based on input from the operation means.
These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter.


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